/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.tomcat.dbcp.pool2.impl;

import java.io.PrintWriter;

/**
 * Strategy for obtaining and printing the current call stack. This is primarily useful for {@link
 * org.apache.tomcat.dbcp.pool2.UsageTracking usage tracking} so that different JVMs and
 * configurations can use more efficient strategies for obtaining the current call stack depending
 * on metadata needs.
 *
 * @see CallStackUtils
 * @since 2.4.3
 */
public interface CallStack {

    /**
     * Prints the current stack trace if available to a PrintWriter. The format is undefined and is
     * primarily useful for debugging issues with {@link org.apache.tomcat.dbcp.pool2.PooledObject}
     * usage in user code.
     *
     * @param writer a PrintWriter to write the current stack trace to if available
     * @return true if a stack trace was available to print or false if nothing was printed
     */
    boolean printStackTrace(final PrintWriter writer);

    /**
     * Takes a snapshot of the current call stack. Subsequent calls to {@link
     * #printStackTrace(PrintWriter)} will print out that stack trace until it is {@linkplain #clear()
     * cleared}.
     */
    void fillInStackTrace();

    /**
     * Clears the current stack trace snapshot. Subsequent calls to {@link
     * #printStackTrace(PrintWriter)} will be no-ops until another call to {@link
     * #fillInStackTrace()}.
     */
    void clear();
}
